Thermal snap circuit breaker with slidable spring biased collar engaging on side of the bimetal



y 9, 1967 T. w. BUTLER ETAL 3 319,031

REAKER TH SL THERMAL SNAP CIRCUIT B IDABLE SPRING BIASED COLLAR ENGAGING 0N E OF THE BIMETA 965 Filed Oct. 23, l 2 eats-Sheet l I /NVENTOR5 WG EuZZer: BYBSYEVQM E-E- p May 9, 1967 T. w. BUTLER ETAL 3,319,031

THERMAL SNAP CIRCUIT BREAKER WITH SLIDABLE SPRING BIASED COLLAR ENGAGING ON SIDE OF THE BIMETAL 2 Sheets-Sheet 2 Filed Oct. 25, 1965 4/! BY Fa ina: 7. Vaughn 44? Ola HTTOF/WE'XS.

United States Patent THERMAL SNAP CIRCUIT BREAKER WITH SLID- ABLE SPRING BIASED COLLAR ENGAGING 0N SIDE OF THE BIMETAL Thomas W. Butler, Ann Arbor, and Bertram T. Vaughn,

Michigan Center, Mich., assignors to Mechanical Products, 1116., Jackson, Mich., a corporation of Delaware Filed Oct. 23, 1965, Ser. No. 503,293 1 Claim. (Cl. 200-138) This invention relates generally to circuit breakers and more particularly to a rocker action, snap acting, circuit breaker.

The aviation industry has found that push-button or rocker action switches are more acceptable to pilots than heretofore used push-pull or toggle action circuit breakers. However, the conventional operating characteristics of push-pull or toggle action circuit breakers are desirable from an electrical standpoint, principally, trip free quick break of the contacts due to a second overload or short circuit condition.

The present invention relates to an improved rocker action circuit breaker that is useable as a conventional rocker action switch by a pilot for normal on-off control of the electrical circuit of an aircraft and in addition provides overload and circuit protection for the circuit. lnterruption of an overload or short circuit condition is effected with a snap action. Furthermore, the operation of the circuit breaker is trip free, the circuit being reclosed upon cooling of a snap acting bimetal when the manual operator of the switch is held to the switch closed condition.

Accordingly, one object of the instant invention is an improved rocker action aircraft circuit breaker.

Another object is an improved rocker action trip free aircraft circuit breaker.

Another object is an improved rocker action trip free circuit breaker having quick break of the electrical contacts.

Other objects and advantages of the instant invention will be apparent in the following description, claim and drawings, wherein:

FIGURE 1 is a top view of an aircraft circuit breaker in accordance with an exemplary constructed embodiment of the instant invention;

FIG. 2 is a cross sectional view taken substantially along the line 22 of FIG. 1;

FIG. 3 is a cross sectional view along the line 33 of FIG. 2;

FIG. 4 is a cross sectional view taken substantially along the line 4-4 of FIG. 2;

FIG. 5 is a cross sectional view taken substantially along the line 55 of FIG. 2; and

FIG. 6 is a view similar to FIG. 2 showing the manual operator and snap acting blade in the contacts open condition.

As best seen in FIGS. 1 and 2 of the drawings an aircraft circuit breaker 10, in accordance with an exemplary constructed embodiment of the instant invention, comprises a mounting plate 12 of U-shaped configuration having a pair of ears 14 and 16 thereon to facilitate mounting on an instrument panel of an aircraft. A manual operator 18 is pivotally secured to a pair of upstanding cars 20 and 22 on the mounting plate 12 by a shaft 24. A spring 26 has one end portion 28 engaged with the manual operator 18 and an opposite end portion 30 interlocked with the plate 12. The inherent resiliency of the spring 26 tends to rotate the manual operator 18 counterclockwise, as seen in FIG. 2.

As best seen in FIG. 2 of the drawings the electrically energized components of the circuit breaker 10 are mounted in an insulating housing 40. A pair of electrical terta-ken substantitally Ininals 42 and 44 extend outwardly of the housing to facilitate connection of the circuit breaker 10 in an electrical circuit. A pair of fixed contacts 46 and 48 are mounted on the terminals 42 and 44, respectively, for engagement with a pair of movable contacts 50 and 52, respectively. The movable contacts 50 and 52 are mounted on a snap acting bimetallic blade 54.

The blade 54 has an aperture 56 therein for the acceptance of a plunger 58. The plunger 58 operates under the control of a finger 60 which is carried by the manual operator 18. The finger 60 has a spherical end portion 62 that is seated in a complementary spherical recess 64 in the plunger 58 to normally retain the manual operator in the contacts closed condition against the bias of the spring 26.

The plunger 58 and blade 54 are normally biased upwardly, as seen in FIG. 2 of the drawings, by a helical compression spring 70 that extends between a seat 72 in the housing 40 and an annular flange 74 that surrounds the plunger 58.

As seen in FIG. 2, the manual operator 18 is in the contacts closed condition and is held in this condition against the bias of the spring 26 due to engagement of the finger 60 with the plunger 58 while the bimetallic blade 54 is held in the contacts closed condition due to the plunger 58.

Upon the occurrence of an overload condition the bimetallic blade 54 snaps to the open condition shown in dotted lines in FIG. 2. When this action occurs a portion of the bias of the plunger 58 against the finger 60 is relieved allowing the spherical portion 62 on the finger 60 to move out of the spherical recess 64 in the plunger 58. Thereafter, the manual operator 18 rotates counterclockwise under the bias of the spring 26. When the manual operator 18 rotates counterclockwise under the bias of the spring 26, the plunger 58 moves upwardly to the position shown in FIG. 6 of the drawings. Reset of the circuit breaker is effected by manually pushing on the manual operator 18 to rotate it clockwise whereupon the finger 60 rides up a conical surface of the plunger 58 forcing the plunger 58 downwardly and reclosing the circuit breaker.

It is to be noted that if a pilot desires to close the circuit breaker against a short circuit or overload condition that the circuit breaker is trip free in operation for intermittent periods. The blade 54 will snap to the dotted line condition shown in FIG. 2 upon heating. However, when the blade 54 cools it will snap to the closed condition shown in full lines in FIG. 2. Such cycling will continue so long as the manual operator 18 is held in the contacts closed condition.

It is to be understood that the specific construction of the improved circuit breaker herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention the scope of which is defined by the following claim.

What is claimed is:

A quick break, trip free, rocker action circuit breaker comprising an insulating housing,

a pair of electrical terminals on said housing,

a pair of fixed contacts on said terminals, respectively,

a snap acting bimetallic blade having a central aperture and a pair of movable contacts on opposite sides of the aperture, said movable contacts being engageable with said fixed contacts, respectively, to complete an electrical circuit through said circuit breaker,

a plunger having a conical portion with a spherical recess therein and a portion extending through the aperture in said bimetallic blade, a collar surrounding said plunger and engageable with said blade on the opposite side thereof from said collar,

a plunger spring engaged with said collar and normally biasing said collar against said blade and said blade against the conical portion of said plunger thereby to bias and said blade toward the contacts open position,

a rookable manual operator having a generally spherical portion engageable in the spherical recess in said plunger to hold said blade and contacts in the contacts closed condition against the bias of said spring, and

a manual operator spring normally biasing said manual operator towards the contacts open condition,

movement of said manual operator towards the contacts closed condition effecting engagement of the spherical portion thereon with the conical portion of said plunger to bias said plunger and bimetallic blade towards the contacts closed condition,

movement of said manual operator towards the contacts open condition efiecting disengagement of the spherical portion thereon from the spherical recess in said plunger whereupon said plunger and bimetallic blade are free to move under the bias of said plunger spring to the contacts open condition,

said snap acting bimetallic blade being movable to the contacts open condition upon the occurrence of a predetermined electrical condition in a circuit containing said circuit breaker irrespective of the condition of said manual operator, movement of said snap acting bimetallic blade to the open condition due to said electrical condition effecting release of said manual operator to permit it to move to the contacts open condition under the bias of said manual operator spring.

References Cited by the Examiner UNITED STATES PATENTS 2,863,965 12/1958 Cardin et al 200113 X 3,013,138 12/1961 Moskv et al. 200-138 20 BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. 

